Electric thermostatic control



Sept. 12, 1933. L. IRELAND ELECTRIC THERMOSTATIC CONTROL Filed Dec. 6, 1929 I m enl or. Lawrence [re/anal Patented Sept. 12, 1933 UNITED STATES PATENT OFFICE Lawrence Ireland, Guelph, Ontario, Canada, as-

signor to The T. Eaton Company, Limited,

Toronto, Canada Application December 6, 1929. Serial No. 412,200

6 Claims.

The principal objects of this invention are to provide asimple and inexpensive means selectively controlled to automatically maintain a substantially constant temperature.

The principal features of the invention consist in the novel arrangement of a plurality of selective electric contacts connected with a heating element and a thermostatic switch member whereby the switch member controls the circuit of the heating element in relation to the temperature surrounding the thermostat.

In the drawing, Figure 1 is a diagrammatic wiring plan of an equipment showing the application of my improved thermostatic control.

Figure 2 is a side elevational detail of the thermostat.

Figure 3 is an end elevational view of the thermostat showing a plan of the dial control connected thereto.

Figure 4 is a part sectional elevational view of the dial control for the thermostat.

Figure 5 is a plan view of the thermostat member.

In the application of the invention herein shown the heating element 1 is provided with a pair of terminals 2 and 3 which are connected to terminal points 4 and 5 of a standard series parallel switch.

The other terminal ends of the heating element are connected to the contacts 6 and 7 of the thermostat 3. These contacts are herein shown in the form of spring fingers secure to the top of an insulating block 9 suitably mounted in the stove or other device containing the heating element.

The block 9 is formed with a longitudinal recess 1-0 in which the contacts 6 and 7 are housed and a contact plate 11 extends across the end of the recess opposite to the end to which the contacts 6 and '7 are secured.

The contacts 6 and 7 are of spring metal and are adapted to engage at their free ends with the underside of the contact plate 11 and close the circuits to the electric elements.

walls 15 and a base 15" which extends over the recess in the block 9 and which is provided with a lug projection 16 on the underside which engages the contacts 6 and "I, depressing same and holding them from contact with the plate 11,

while the upper block is in position, but if the upper block is removed the contacts will spring upwardly and engage the plate 11.

The contact plate 11 is provided with a terminal binding screw 17 at one side to which a Wire 18 connected with the contact 19 of the series parallel switch is connected.

Secured to one of the side walls of the block 12 is a series of contact plates 20, the lower one being in electrical contact with the plate 11 and the others being insulated each from the other.

A thermostatic arm 21, preferably formed of a bi-metallic strip is secured to the closed end 22 of the block 12 and extends over the open section thereof.

Secured to the bi-metallic portion is a metal plate 23 which is formed withupwardly turned lug portions 2! which carry contact points 25 which engage in sliding contact with the contact plates 20 on the side wall of the block 9.

A flexible electric conductor 26 is connected to the contact carrying plate 23 at one end and to the fastening bolts 27 at the other end which engage in electrical contact with the contacts 6 and *7 and therefore with the element terminals 2 and 3.

A dial knob 28 is arranged in a suitable position on the device containing the heating element and to said knob is secured a rotary contact plate 29 which is adapted. on rotation to engage with a plurality of circumferentially arranged contacts 30 which are preferably in the form of spring blocks 31 arranged within an insulating block 32.

The contact 30 is connected to the wire 18 and consequently is connected with the contact plate 11 of the thermostat member.

Each of the other contacts 30 are individually connected by the wires 33 to the series of contact plates 20.

The rotatable plate 29 connected with the dial knob maintains a constant connection with the contact 30 and the current supply wire 18, and

when the dial knob is turned to move the plate into engagement with the other contacts 39 it will have the eifect of connecting each of said contacts with the wire 18.

The dial knob is provided with graduations indicating temperatures and a pointer is arranged adjacent thereto to indicate the position of the plate 29 in respect to the contacts 30.

The bi-metallic strip forming the thermostatic switch arm is adapted to move the contact points carried thereby successively into contact with the series of plates 20 in accordance with the temperature of the enclosure in which the thermostat is located and which is heated by the element 1.

Each successive plate of the series 20 represents a definite range of temperature, for instance, the first plate above the plate 11 Will represent 250, the next 300; the next 350 and so on, so that if the plate 29 connected with the dial knob is turned to cover the contact connected with the 356 plate, it will also connect the 300 and 250 plate, consequently when the current is turned on and the element 1 is heated the thermostatic arm will move the contacts carried thereby upwardly, engaging the several plates in succession until the temperature reaches 350 when the contacts will have moved past the 350 plate, but as the plate 29 does not close the circuit to the next succeeding plate 20 the current will be cut 051 by the automatic switch arm, but as the heat within the compartment dissipates, the thermostatic arm will move its contacts downwardly bringing it again in contact with the last of the plates connected through to the source of current and thus the thermostatic arm will maintain the temperature at the desired point.

It will thus be readily understood that the dial member may be set to any desired temperature and the thermostatic arm will operate to cut off the supply of electric current to the heating element when that temperature has been reached.

The device is extremely simple and can be readily installed. If for any reason the thermo stat member should become inoperative, it is merely necessary to remove the upper block 12 and allow the contacts 6 and 7 to move into engagement with the plate 11 which will thus close the circuit to the heating element so that it may be used in the ordinary way by the manipulation. of the switch.

It will be understood that the dial knob 28 and its co-operating parts may be arranged in any desired location, remote from the heating element so that the temperature to be sustained in the heat compartment may be regulated from a remote point.

What I claim as my invention is:-

1. In an electric thermostatic control, an insulating block, a second insulating block removably associated with the former insulating block, said first mentioned block having a spring contact and a metal plate extending transversely to engage or disengage said spring contact in accordance with the removal or replacement 'respectively of said second block, a thermostatic element carried by the latter block, and switch means associated with said latter block to substitute said spring contact when the one block is in position on the other, said switch means including a movable element operated by the thermostatic element, and said metal plate having a perpendicular portion for engagement with said movable element.

2. In an electric thermostat control, the combination of an insulating block having a fixed contact and a depressible contact co-operating therewith, a second insulating block removably mounted on said former block and when in position thereon holding said depressible contact from engagement with the fixed contact, a thermostatically actuated contact carried by said second block and electrically connected with said depressible contact, and a plurality of contacts engagcable by thermostatically operated contact in its travel and adapted to be selectively energized.

3. In an electric thermostat control, the combination of an insulating block having a fixed contact and a depressible contact co-operating therewith, a second insulating block removably mounted on said former block and when in position therecn holding said depressible contact 1 engagement with the contact, an upstanding fiange of insulating material at one end of said removable block, a plurality of stationary contacts supported in side-by-side relation by said upstanding flange and adapted to be selectively energized, a thermostatic element having one end anchored at the end of said removable block, and a contact connected with said depressible contact and moved by the free end of said thermostatic element across said flange contacts.

4. In an electric thermostat control, the combi 'ion of an insulating block adapted to be y secured to a supporting structure and havn elongated therein, a fixed contact ng a strip of spring metal secured l of the s and extending lonat the Our gitudino iy contact 15 fixed contact and being depressiblc out GI 01 ment therewith, a second insulating blocr. removably mounted on said firstmentioned block nd having a protuberance contacting s1 con tot strip at a point intermediate its length to depress the same when the removable bio-cl: in position, said removable block havi mounted thereon and removable therewith thermostatic control switch comprising a thermostatically controlled contact connected with said spring contact, and a plurality of stationary contacts co-operating therewith and adapted to be selectively energized.

5. An electric thermostat control as claimed in claim 2 in which one of said plurality of contacts forms part of or is electrically connected with the stationary contact of said first mentioned block.

6. In an electric thermostat control, the combination of an insuiating block having a fixed contact and a deprecible contact co-operating therewith, a second insulating block removably mounted on s id to mer block and when in pon thereon helm. g said depressible contact engagement with the contact, an upstanding fiange of insulating mater al at one end of said removable bl ciz, a plur y of stationary contacts supported in side-by-side relation by said upstanding flange and adapted to be selectively energized, a strip of bi-metallic metal secured at one end to the removable block, and a strip of metal secured to the free end of said bi-metallic strip and having a laterally turned contact portion at the end for contact with said flange contacts.

LAWRENCE IRELAND. 

